1. Technical Field
The present invention relates generally to an improved data processing system and in particular to a method and apparatus for processing a data stream in a data processing system. Still more particularly, the present invention relates to a method and apparatus for processing a data stream including audio and video data.
2. Description of the Related Art
Multimedia, the presentation or transfer of information through more than one medium at any time, is a fast growing segment of the computer industry with many applications being developed, which incorporate various features of multimedia. Additionally, many businesses are using multimedia to present information to consumers. Multimedia combines different forms of media in the communication of information to a user through a data processing system, such as a personal computer. A multimedia application is an application that uses different forms of communications within a single application. For example, multimedia applications may communicate data to a user through a computer via audio and video simultaneously. Such multimedia applications are usually bit intensive, real time, and very demanding, requiring ample processing power in the data processing system. Users may access in the multimedia, for example, in the form of video games or movies on a digital video disk (DVD) or through a communications link.
With MPEG decoding, a system stream containing video and audio packets is received at an input layer. The input layer is used to read data into an internal buffer that can be processed. The data can be retrieved either by file reads or through a network client passing data. The end result is a buffer that can be processed and parsed by the system layer. The system layer will take the data in the input buffer and parse the data until it hits packet starts. MPEG data is comprised of a system stream that contains multiple packets. These packets may be audio or video data packets. Each audio or video packet is designated by a packet start and followed immediately after by packet information such as the packet type, audio or video, length of the packet and possibly PTS values. Past this descriptive information is the data that will be sent to the respective audio and video decoders. The amount of data sent is based on the packet length that is decremented as the packet information is processed and skipped over.
For many MPEG applications, data rates are very high and video decoding is where most of the processing power is required. It is desirable to efficiently process audio as well as to continue to process video to improve frame rates. In some instances, audio underruns may occur causing undesirable effects in the multimedia presentation. Therefore, it would be advantageous to have an improved method and apparatus for processing multimedia data streams.
It is one objective of the present invention to provide an improved data processing system.
It is another objective of the present invention to provide a method and apparatus for processing a data stream.
It is yet another objective of the present invention to provide a method and apparatus for processing a data stream including audio and video data.
The foregoing objectives are achieved as is now described.
The present invention provides a method and apparatus for processing a data stream including audio and video data in which high data rates and throughput is required. Thresholds are employed to control the processing of video and audio data in a data stream. Video data is decoded in response to a comparison of audio and video data to threshold values. Additionally, another threshold value is employed to control buffers storing audio data in response to an underflow of audio data.
Additionally, these thresholds may be dynamically changed in response to configurations present on different processing systems.
The above as well as additional objectives, features, and advantages of the present invention will become apparent in the following detailed written description.